skill-installer

A tool for installing Claude Code skills from skills.sh, GitHub, or a direct SKILL.md download. Claude Code skills are reusable instructions that add focused abilities to the coding assistant.

In plain words
What is it for?
It helps install new skills globally, detect naming conflicts, and handle the supported installation source types.
Why use it?
It checks for an existing skill and requires confirmation before installing or replacing one.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/0oooooooo0/skillless/skill-installer
Any agent
npx skills add 0oooooooo0/skillless --skill skill-installer
Clone the repo
git clone --depth 1 https://github.com/0oooooooo0/skillless

Made for: Claude Code, Codex.

Per session 0 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 693 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00000 $0.00693
Opus 5 $0.00000 $0.00347
Sonnet 5 $0.00000 $0.00139
Haiku 4.5 $0.00000 $0.00069

Measured 2d ago against content hash 4a05c29837aa, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

skill-installer scanned grade A with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

2. Download: `curl -sL https://raw.githubusercontent.com/{owner}/{repo}/refs/heads/main/{path-to-SKILL.md}`
skills/skill-installer/SKILL.md · 83 lines

How it starts

The opening of the file, as written. The whole thing — 83 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Skill: skill-installer

Install Claude Code skills from various sources.

user-invocable: false description: Handles skill installation from skills.sh, GitHub, or direct SKILL.md download. Always confirms with user before installing. allowed-tools: [Read, Write, Bash, WebFetch, Glob, AskUserQuestion]

Instructions

When called with a skill to install, determine the source type and follow the appropriate flow.

Pre-installation Checks

  1. Conflict detection: Check if a skill with the same name already exists:
    Glob: ~/.claude/skills/{skill-name}/SKILL.md
    
  2. If already installed, inform the user and ask if they want to update/overwrite.
  3. Always confirm with the user before proceeding with installation.

Installation by Source Type

Type: installed

The skill is already installed locally. Inform the user:

"This skill is already available on your system. You can use it right away."

Type: skills-add

The skill is listed on skills.sh and can be installed via npx. Run:

npx skills add -y -g {owner/repo}
  • -y: skip confirmation prompts
  • -g: install globally to ~/.claude/skills/
  • Format: {owner/repo} (e.g., vercel-labs/agent-skills)
  • To install a specific skill from a multi-skill repo: {owner/repo}/{skill-name}

IMPORTANT: The old npx skillsadd package is deprecated and no longer works. Always use npx skills add.

If npx skills add fails (e.g., "No valid skills found"), fall back to direct GitHub download:

  1. Find the SKILL.md path via: https://api.github.com/repos/{owner}/{repo}/git/trees/main?recursive=1
  2. Download: curl -sL https://raw.githubusercontent.com/{owner}/{repo}/refs/heads/main/{path-to-SKILL.md}
  3. Save to ~/.claude/skills/{skill-name}/SKILL.md
Type: github-plugin

The skill is part of a GitHub-hosted plugin. Guide the user:

"This skill is available as a GitHub plugin. To install, run:

/plugin install {github-url}
```"
Type: skill-md

A standalone SKILL.md file that can be downloaded directly:

Read the full file on GitHub · 83 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 83 lines · 0 tokens per session scan A 4a05c29837aa

Subscribe to this mod's changes

skill-installer is a skill published in the GitHub repository 0oooooooo0/skillless (38 stars, last pushed 6mo ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 693 tokens. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.